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A Segmentation Algorithm of the Connected Word Speech by Statistical Method
조정호,홍재근,김수중,Cho, Jeong-Ho,Hong, Jae-Keun,Kim, Soo-Joong 대한전자공학회 1989 전자공학회논문지 Vol. No.
本 論文에서는 音聲信號의 音素分割을 위한 統計的인 方法을 硏究하였다. 이 方法은 3個의 AR 모델을 使用하여, 이 中 2個의 모델은 音聲의 스펙트럼 變化前 및 變化後의 安定된 部分에서 求해지고 이들 間의 距離가 커지면 音素가 바뀐 것으로 간주된다. 다른 한 모델은 두 固定 모델 사이에 位置하며 音素間의 境界를 推定하는데 使用된다. 이 音素分割 알고리듬을 連結音에 對해 試驗해 본 結果, 從來의 方法에 비해 音素의 境界點을 좀더 正確히 찾을 수 있고, 또한 過度分割 誤謬도 줄일 수 있었다. A statistical approach for the segmentation of speed signals is described in this paper. The main idea of this algorithm is the use of three AR models. Two fixed models are identified at the stationary parts of the signal before and after the spectral change. Changes are detected when the distance between these two models is high. Another model is located between two fixed models and is used to estimate spectral change time. This segmentation algorithm has been tested with connected words and compared to classical methods. The results showed that it can provide more accurate locations of boundaries of segments and can reduce the amount of oversegmentation.
Vertically Stacked Graphene-Semiconductor Heterostructures for Large-Area Electronics
Jeong Ho Cho(조정호) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
We demonstrate a new device architecture for flexible vertical Schottky barrier (SB) transistors based on graphene-semiconductor–metal heterostructures and ion gel gate dielectrics. The vertical SB transistor structure was formed by (i) vertically sandwiching a semiconductor layer between graphene and metal electrodes and (ii) employing a separate coplanar gate electrode bridged with the vertical channel through an ion gel. The high intrinsic capacitance of the ion-gel gate dielectric facilitated modulation of the SB height at the graphene/channel heterojunction at a gate voltage lower than 2 V. The resulting vertical SB transistors exhibited a high current density, a high on-off current ratio, and excellent operational and environmental stabilities. The facile, large-area, and room-temperature deposition of both semiconductors and gate insulators integrates with transparent and flexible graphene opens up new opportunities for realizing graphene-based future electronics.
전사 인쇄에 의한 3D와 다층의 Pt 전극의 CO가스 흡착
정윤서 ( Yoon-seo Jeong ),최유정 ( You-jeong Choi ),신정희 ( Jeong-hee Shin ),정영훈 ( Young-hun Jeong ),박종후 ( Jong-hoo Paik ),윤대호 ( Dae-ho Yoon ),조정호 ( Jeong-ho Cho ) 한국센서학회 2020 센서학회지 Vol.29 No.4
Three-dimensional (3D) multilayered Pt electrodes were fabricated to develop a porous electrode using a pattern-transfer printing process. The Pt thin films were deposited using a transferred sputtering pattern having a 250 nm line width on the substrate, and the uniform line patterns were efficiently transferred using our proposed method. Temperature-programmed desorption (TPD) analyses were used to evaluate the porosity of the electrodes. It was possible to distinguish between two resolved maxima at 168 and 227 ℃, which could be described in terms of desorption reactions on the Pt (111) planes. The results of the TPD analysis of the 3D and multilayered Pt electrodes prepared through transfer printing were compared to those of an electrode fabricated through screen printing using a commercial Pt-carbon paste commonly used as porous electrodes. It was confirmed that the 3D multilayered electrodes exhibited a desorption concentration approximately 100 times higher than that of the Pt-carbon composite electrode, and the desorption concentration increased by approximately 0.02 mg/mol per layer. The 3D multilayered electrode effectively functions as a porous electrode and a catalyst.
(Bi<sub>1?2</sub>Na<sub>1?2</sub>)<sub>1-x</sub>Ca<sub>x</sub>TiO<sub>3</sub> 세라믹스의 압전 특성 및 상전이 거동
이용현,조정호,김병익,최덕균,Lee, Yong-Hyun,Cho, Jeong-Ho,Kim, Byung-Ik,Choi, Duck-Kyun 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.5
$(Bi_{1/2}Na_{1/2})TiO_3$-based ceramics have been intensively studied as lead-free piezoelectric ceramics. In this study, the piezoelectric properties and phase transition behaviors of BNT based solid solution $(Bi_{0.5}Na_{0.5})_{1-x}Ca_xTiO_3$ ($X=0.01{\sim}0.25$) were investigated. The morphotropic phase boundary(MPB) zone which BNT is transformed from rhombohedral to cubic structure was appeared by adding $CaTiO_3$ with 0.12 mol by the measurement of permittivity and X-ray diffraction. The behavior which ferroelectric BNT with adding $CaTiO_3$ was changed to antiferroelectric and paraelectric state was confirmed by the measurement ofhysterisis loop and depolarization temperature as a function of temperature. As $CaTiO_3$ concentration was increased, the phase transition temperature was decreased. The piezoelectric properties were highest at 0.01 mol of $CaTiO_3$ concentration. The electromechanical coupling factor($K_t$) and mechanical quality factor($Q_m$) were 42% and 254, respectively.
강경민,조정호,남중희,고태경,전명표,Kang, Kyung-Min,Cho, Jeong-Ho,Nam, Joong-Hee,Ko, Tae-Gyung,Chun, Myoung-Pyo 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.7
The most widely used piezoelectric ceramics are lead oxide based ferroelectrics (PZT). However, the toxicity of lead oxide and its high vapor pressure during processing have led to a demand for alternative lead-free piezoelectric materials. We synthesized Lead-free piezoelectric ceramics of $0.96(K_{0.5}Na_{0.5})NbO_3-0.04SrZrO_3+x$ mol% $ZrO_2$ [KNN-SZ+$xZrO_2$; x= 0~0.10] doped with 0.1 wt% $MnO_2$ by a conventional solid state method. We investigated the piezoelectric properties and microstructures of these disk samples sintered in reduced atmosphere in order to evaluate the possibility of the multilayered piezoelectric ceramics having the base metal such as Ni as a internal electrode. All of these KNN-SZ samples sintered in 3%$H_2-97%N_2$ atmosphere at $1,140^{\circ}C$ exhibit pure perovskite structure irrespective of the content of $ZrO_2$. Meanwhile, the sintering denisty and piezoelectric properties such as $K_p$, $Q_m$ and $d_{33}$ of KNN-SZ samples as a function of $ZrO_2$ content show the maxima ($k_p$=28.07%, $Q_m$= 101.34, $d_{33}$= 156 pC/N) at x= 0.04 and it is likely that there is some morphotropic phase boundary(MPB) in this KNN-SZ+$xZrO_2$ composition system. These results indicate that the ceramic composition is a promising candidate material for applications in lead free multilayer piezoelectric ceramics.